This invention relates to an inflatable pipe plug.
There are numerous occasions when various pipes, such as water pipes and sewer pipes, should be temporarily plugged. Often this can be conveniently done by using an inflatable rubber plug which can be pulled through the pipe by means of a cable secured to the plug, and then, when the plug is at a desired location, air can be sent into the plug through a conduit lying generally parallel to the cable of attached to it. When air pressure is applied, the plug is expanded into very firm contact with the walls of the pipe. As a result, liquid in the pipe is kept from flowing past the plug. Later, the plug can be deflated and withdrawn.
Considerable pneumatic pressures may need to be applied, particularly where the hydraulic pressure is relatively high in the pipe, and the air pressure must be sufficient to retain the plug against this hydraulic pressure. Furthermore, the plug itself has to be able to expand without becoming weakened by frequent expansion and relaxation. Separation between the rubber portion and a metal end portion is to be avoided, and the rubber needs reinforcement.
In the past, some of these inflatable plugs have tended to give way under pressure. Others have tended not to be able to close off the pipe properly so as to prevent passage of liquid, because of the plug's inability to retain sufficient pressure or inability to expand, or for other such reasons. There have been points of weakness, where various layers or laminations of the plug have tended to come apart.
The present invention is intended to solve these various problems.